Neutralizing apparatus



W. H. CHAPMAN NEUTRALIZING APPARATUS I July 9, 1940.

Filed Feb. 24, 1940 Inventor I I MZZL a/n C imp/ream 83 g Patented July 9, 1940 UNITED STATES PATENT OFFICE NEUTRALIZIN G APPARATUS Application February 24, 1940, Serial No. 320,690

16 Claims.

My present invention relates to apparatus for use in neutralizing static electric charges in sheets of paper and the like.

For many years, I have been actively engaged in the problem of neutralizing charges of static electricity. My present invention may be introduced by referring to one of my early patents, United States Letters Patent No. 983,536, granted February 7, 1911. This patent related to methods of removing or neutralizing static electricity by charging an insulated conductor with a high potential alternating current with the body to be treated within the electrostatic field thus created. In this electrostatic field, I disposed a fine grounded wire parallel with the conductor.

While this method was effective to neutralize an object having a static electric charge, I was unable to provide any practicable apparatus for applying this method under commercial conditions.

Among the difiiculties encountered, the most serious was the corrosion of the fine wire with the consequent interruption of service. The use of a wire sufficiently fine to be efiective proved objectionable because it was too easily broken by moving objects and by the operators of machines which such apparatus was intended to serve.

My present invention relates to apparatus for carrying out the method set forth in my prior patent above referred to. In general, my present invention includes an insulated conductor to be connected to a source of high potential alternating current. I provide a fine grounded wire of non-corrosive stock with portions of such wire disposed to intersect a plane perpendicular to the sheet or other object to be treated and including the insulated conductor. By this construction, I establish a relatively wide neutralizing field intermediate the conductor and the object to be neutralized.

In practice, it is important to use noncorrosive wire substantially in the range of .01 to .005 of an inch in diameter and the potential employed must be sufficient to induce a corona discharge on the particular wire employed. With the range of wire set forth, suitable current is substantially in the order of from fifteen thousand to five thousand volts with the voltage decreasing as the diameter of the wire decreases.

While disposition of the fine wire to create a substantial neutralizing field is of importance, I have also provided means to protect the fine wire and to avoid the failure of my apparatus and the danger of sparks should the fine wire break. I accomplish this result by grounded means holding the wire in desired relation to the conductor throughout the portions of the wire establishing the neutralizing field.

In practice, I Wind the fine wire around the insulated conductor and anchor it in place by means of a relatively coarse wire wound about the insulated conductor with its pitch opposite to that of the fine wire. Both wires are anchored to the insulated conductor adjacent its ends by grounded clamps. By this construction, I am able to provide eflicient, simple apparatus of a unitary nature that may be easily and conveniently installed and produces a neutralizing field in all directions surrounding it as is often needed between the carrier tapes on a printing press.

In the accompanying drawing, I have illustrated an embodiment of my invention from which its many novel features and advantages will be readily apparent. In the drawing:

Fig. 1 shows, in perspective, a typical installation of neutralizing apparatus in accordance with my invention, and

Fig. 2 is a vertical section through the apparatus shown in Fig. 1.

In the drawing, I have indicated at l a tie rod of a printing press as representative of equipment, the use of which results in the development of a charge of static electricity in the sheet or other body S.

Apparatus in accordance with my invention consists of a metal conductor bar 2 having one end 2 exposed from its sheath of insulation 3 to receive the cap 4. While the insulating sheath may be of any suitable material, such materials as Bakelite may be mentioned as well adapted for use in apparatus in accordance with my invention. The cap 4 carries a contact 5 in the line 6 from the transformer "l establishing a source of high potential alternating current. For practical purposes, the potential with which I. am concerned may be considered as ranging from five to fifteen thousand volts.

At 8 I have shown a fine wire spirally wound about the insulated conductor and anchored by clamps 9 adjacent each end of the insulated conductor, which clamps are connected to clamps ID on the tie rod l by the metal rods II. By this assembly, the wire 8 is eifectively grounded through the press.

The wire 8 is of such non-corrosive stock as stainless steel and ranges from .01 to .005 inch in diameter. When a potential is employed sufficient to induce a corona discharge in the wire ,8, a neutralizing field is established by which the sheet S may be completely neutralized.

In practice, the neutralizing apparatus is mounted in the press or other equipment in proximity to the sheet S. The precise distance of the apparatus from the sheet S is not critical, for example, it will generally be found to serve its purpose at a distance of from three to four inches from the sheet when the speed of the material being treatedis not excessive. It should be noted, however, that by placing the apparatus comparatively close to the moving sheet, the sheet S may be provided with a small charge of the opposite polarity and this result, as men tioned in my United States Letters Patent No. 1,782,712, is sometimes desirable as it permits the anticipation of a subsequent charge to be developed where direct neutralization is either inconvenient or impossible.

It should be noted that in accordance with my invention, the potential may be decreased with the diameter of the wire. non-corrosive. wire of '.005 inch in'diameter, very excellent results are secured with a potential of five thousand volts.

With suchfine wires as I have set forth, it is necessary to protect them from mechanical abrasion and to avoid. the danger of sparks if the fine wire were broken and some portions of. it left ungrounded. This is a particularly important consideration on ,rotogravure presses on which inflammable ink is used.

To accomplishthis result, I protect the fine Wire 8 by an auxiliary grounded conductor. Preferably, the grounded conductor holds the wire 8 against the insulating sheath of the charged conductor so that even if the wire broke in several places, the safe and efficient operation of my apparatus would not be materially affected.

In practice, I prefer to employ a relatively coarser wire 12 of non-corrosive stock that may be spirally wound about the insulated conductor with its pitch opposite to that of the fine wire. The pitch of the wire 8 may be about two turns to the inch, although the number of turns is not critical while the pitch of the wire i2 may be about one turn to the inch. This relationship is such that eachconvolution of the wire 8 is held against the insulating sheath of the charged conductor and accordingly well protected. The wire i2 is conveniently anchored by the grounded clamps Hi. The grounding of the wire at both ends is desired as an added security.

In accordance with my invention, I provide simple, safe, reliable, and efficient neutralizing apparatus harmless to touch that may be easily installed in any machine, the use of which develops a static electric charge in an object in which the presence of such a charge is undesirable.

What I therefore claim and desire to secure by Letters Patent is: I

1. Apparatus for use in neutralizing the static charge of an object such as a sheet or the like, said apparatus comprising an insulated conductor to be connected to a source of high potential alternating current and to be disposed in desired relation to the-object and grounded means, said grounded means comprising a fine non-corrosive wire disposed to present'a plurality of portions intersecting a plane perpendicular to said object and inclusive of said conductor to create a grounded neutralizing field of substantial width.

2. Apparatus for use in neutralizing the static charge of an object such as a sheet or the like, said apparatus comprising an insulated conductor to be connected to a source of high potential I is in the order of .01 to .005 of an inch in diameter.

4. Apparatus for use in neutralizing the static charge of an object such as a sheet or the like, said apparatus comprising an insulated conductor connected to a source of high potential alter- V nating current and disposed in desired relation For example, with to the object, a fine non-corrosive grounded wire disposed to present a plurality of portions intersecting a plane perpendicular to said object and inclusive of said conductor to create a grounded neutralizing. field of substantial width intermediate said conductor and said object, said Wire being in the order of-.01 to .005 of an inch in diameter, and said current being in the order of fifteen thousand to five thousand volts.

. 5. Apparatus for use in neutralizing the static charge of an object such as a sheet or the like, said apparatus comprising an insulated conductor connected to a source of high potential alternating current and disposed in desired relation to'the object, a fine non-corrosive grounded wire disposed to present a plurality of portions intersecting a plane perpendicular to said object and inclusive of said conductor to create a grounded neutralizingfield of substantial width intermediate said conductor and said object, said wire being in the order of .01 to .005 of an inch in diameter, and said current being of suificient voltage to induce a corona discharge on the wire em ployed.

' 6. Apparatus for use in neutralizing the static charge of an object, such as a sheet or the like, said apparatus comprising an insulated conductor to be connected to a source of high potential alternating current and to be disposed in desired relation'to the object, a fine non-corrosive wire disposed to present a plurality of portions inter- *sectin'g a plane perpendicular to said object and inclusive of said conductor to create a neutralizing field of substantial width intermediate said conductor and said object, and means to ground said wire at least at two points, each adjacent :1.

one end of said field.

'7. Apparatus for use in neutralizing the static charge of an object such as a sheet of paper or the like, said apparatus comprising a conductor to be connected to a source of high potentialalternating current and to be disposed in desired relation to the object, an insulating sheath for said conductor, and a fine non-corrosive grounded wire wound about said insulating sheath.

8. Apparatus for use in neutralizing the static charge of. an object such as a sheet of paper or the like, said apparatus comprising a conductor to be connected to a source of high potential alternating current and to be disposed in desired relation to, the object, an insulating sheath for said conductor, a fine non-corrosive grounded Wire wound about said insulating sheath, and said Wire being in the order of .01 to .005 of an inch in diameter.

9. Apparatus foru'se in neutralizing the static charge of an object such as a sheet of paper or the like, said apparatus comprising a conductor to be connected to a source of high potential alternating current and to be disposed in desired relation to the object, an insulating sheath for said conductor, a fine non-corrosive wire wound about said insulating sheath, and grounded clamp means to hold each end of said wire to said insulating sheath.

10. Apparatus for use in neutralizing the static charge of an object such as a sheet of paper or the like, saidapparatus comprising a conductor to be connected to a source of high potential alternating current and to be disposed in desired relation to the object, an insulating sheath for said conductor, a fine non-corrosive wire wound about the insulating sheath for said conductor, grounded clamp means to hold each end of wire to said insulating sheath, and grounded means to hold said wire to said insulating sheath intermediate said clamp means.

11; Apparatus for use in neutralizing the static charge of an object such as a sheet of paper or the like, said apparatus comprising a conductor to be connected to a source of high potential alternating current and to be disposed in desired relation to the object, an insulating sheath for said conductor, a fine non-corrosive wire laid along the surface of said insulating sheath, a second relatively coarser wire of non-corrosive stock wound about said insulating sheath to hold said first wire securely in position, and grounded means to clamp said wires to said insulating sheath.

12. Apparatus for use in neutralizing the static charge of an object such as a sheet of paper or the like, said apparatus comprising a conductor to be connected to a source of. high potential alternating current and to be disposed in desired relation to the object, an insulating sheath for said conductor, a fine grounded wire spirally wound about said insulating sheath, and a second relatively coarser grounded wire spirally wound about said insulating sheath and said fine wire to anchor said fine wire to said insulating sheath at a plurality of points, both of said wires being of non-corrosive stock.

13. The device of claim 12 in which the pitch of the coarser Wire is opposite to the pitch of the fine wire.

i i. The device of claim 12 in which the pitch of the coarser wire is opposite to the pitch of. the fine wire and the fine wire has substantially two turns to the inch and the coarser wire has substantially one turn to the inch.

15. Apparatus for use in neutralizing the static charge of an object, such as a sheet or the like, said apparatus comprising a conductor to be disposed in desired relation to the object, an insulating sheath for the conductor, a fine non-corrosive grounded wire spirally wound about and anchored to said insulating sheath, said wire being substantially in the order of .01 to .005 inch in diameter so that when said conductor is connected to a source of high potential alternating current adequate to induce a corona discharge on said wire, a neutralizing field is established.

16. Apparatus for use in neutralizing the static charge of an object such as a sheet of paper or the like, said apparatus comprising a conductor to be connected to a source of. high potential alternating current and to be disposed in desired relation to the object, an insulating sheath for said conductor, a relatively coarse wire of noncorrosive stock wound about said insulating sheath, a relatively fine wire held by said first named wire to said insulating sheath, and grounded means to clamp said first named Wire to said insulating sheath.

WILLIAM H. CHAPMAN. 

